The present invention relates to turbochargers for internal combustion engines.
An exhaust gas-driven turbocharger is a device used in conjunction with an internal combustion engine for increasing the power output of the engine by compressing the air that is delivered to the air intake of the engine to be mixed with fuel and burned in the engine. A turbocharger comprises a compressor wheel mounted on one end of a shaft in a compressor housing and a turbine wheel mounted on the other end of the shaft in a turbine housing. Typically the turbine housing is formed separately from the compressor housing, and there is yet another center housing connected between the turbine and compressor housings for containing bearings for the shaft. The turbine housing defines a generally annular chamber that surrounds the turbine wheel and that receives exhaust gas from an engine. The turbine assembly includes a nozzle that leads from the chamber into the turbine wheel. The exhaust gas flows from the chamber through the nozzle to the turbine wheel and the turbine wheel is driven by the exhaust gas. The turbine thus extracts power from the exhaust gas and drives the compressor. The compressor receives ambient air through an inlet of the compressor housing and the air is compressed by the compressor wheel and is then discharged from the housing to the engine air intake.
A turbocharger typically includes a heat shield or shroud disposed between the turbine assembly and the center housing for shielding the center housing from direct contact with the hot exhaust gas. In some cases, the heat shield is coaxially centered in the assembly by engagement with the turbine housing. Consequently, during assembly, before the turbine housing is mated with the center housing, there is nothing to keep the heat shield centered on the center housing, and it can fall downward whenever the partial assembly is oriented with its central longitudinal axis non-vertical.
While the above-described turbochargers function well, further improvements are sought.